1. Field of the Invention
The present disclosure relates to a liquid crystal display (LCD) device, and more particularly, to an LCD device being capable of easily discharging a unnecessary charges, e.g., a static electricity.
2. Discussion of the Related Art
The liquid crystal display (LCD) device, which is adequate to display moving images and has an advantage in a contrast ratio, is widely used for a display device such as a television and a monitor. The LCD device uses optical anisotropy and polarization properties of liquid crystal molecules.
The LCD device includes a liquid crystal panel as an essential element. Two substrates with a liquid crystal layer therebetween are attached to form the liquid crystal panel. The alignment of the liquid crystal molecules is changed by an electric field generated in the liquid crystal panel such that images can be displayed by controlling light transmissivity.
Since an active matrix LCD device using a vertical electric field has excellent characteristics such as high resolution and display of moving images, the active matrix LCD device has been widely used. Unfortunately, the device using the vertical electric field has a disadvantage in a viewing angle.
To overcome the disadvantage in the viewing angle, various methods, e.g., an in-plane switching (IPS) mode LCD device, have been developed.
FIG. 1 is a schematic cross-sectional view of the related art liquid crystal panel for the IPS mode LCD device. As shown in FIG. 1, the liquid crystal panel for the IPS mode LCD device includes a first substrate 10 as an array substrate, a second substrate 20 as a color filter substrate, and a liquid crystal layer 30 therebetween.
On the first substrate 10, a common electrode 12 and a pixel electrode 14 are formed. A horizontal electric field L is generated between the common and pixel electrodes 12 and 14. The liquid crystal molecules 31 are driven by the horizontal electric field L. On the second substrate 20, a black matrix 21 shielding a non-display region and a color filter layer 23 including red, green and blue color filter patterns are formed.
In addition, first and second polarization plates 40 and 50 are formed on outer sides of the first and second substrates 10 and 20, respectively. An optical axis of the first polarization plate 40 is perpendicular to an optical axis of the second polarization plate 50.
Since the liquid crystal molecules 31 are driven by the horizontal electric field L between the common and pixel electrodes 12 and 14 on the first substrate 10, the viewing angle of the IPS mode LCD device is improved.
On the other hand, by unnecessary charges, e.g., a static electricity, the electrodes and the lines of the IPS mode LCD device are damaged and an alignment of the liquid crystal molecules 31 is misaligned.
Particularly, since there is no metal element on the second substrate 20, the static electricity on the second substrate 20 cannot be discharged. To prevent damages from the static electricity, a transparent conductive material layer 60 as an anti-static layer is formed on an outer surface of the second substrate 20. The transparent conductive material layer 60 is electrically connected to the first substrate 10 using a silver dot (not shown) or a conductive tape (not shown) such that the static electricity on the second substrate 20 is discharged through the first substrate 10.
However, when the silver dot or the conductive tape is formed, there may be damages on the second polarization plate 50. In addition, a process time is increased. Moreover, a viewing angle is violated by the silver dot or the conductive tape. Furthermore, since there is a step difference on a top surface of an element on the first substrate 10, a problem of crack is generated on the silver dot under a high temperature condition such that the static electricity cannot be discharged. As a result, there are damages on the LCD devices.